Start with the current 120-second cycle
Casual and Classic both use a 120-second infection duration. Count from the start of the current infection cycle. The older five-minute wording does not match either active ruleset, so it is not a safe basis for a treatment decision.
The default is to act as soon as the infected state appears. If you hold and its approximate synthesis window still fits, move to safety and start the first step. If that window no longer fits, use a ready dose of before synthesis. Pills delay infection; they do not cure it.
This default has two conditions. The treatment must be in the Responder’s Inventory, and the remaining time must cover the action you choose. Gene Therapy needs about 25 seconds for synthesis before the second use. A Pill dose is most reliable when its repeated-use resistance has reset. The cost of using Pills is one of three doses and a new repeated-use state. The alternative is to keep moving toward treatment, but that becomes worse as the 120-second boundary approaches.
Do not wait for an exact final-second threshold. The timer does not include the time needed to equip an item, reach cover, or perform the second Gene Therapy input. A positive mathematical margin can still be too small for the situation on screen.
Identify the exposure before reading health
Current health does not produce one universal infection chance. The exposure action chooses one of four curves: ordinary zombie melee, the beginning of a grab, the bite after a grab, or a Shambler toxic cloud. Health then selects the point on that curve.
For ordinary melee, the curve is 50% from 0 through 10 HP. It falls linearly to 5% at 50 HP, reaches 0% at 60 HP, and remains 0% through 100 HP. Healing to 60 HP therefore crosses the last nonzero point for ordinary melee before resistance. The cost is the recovery item and time spent using it. If healing is unavailable, the alternative is to reduce exposure by leaving avoidable contact.
That threshold does not cover the other actions. A grab beginning has a 0% curve value, while the bite has a 100% value at every health. A Shambler cloud remains 5% at 80 through 100 HP and rises as health falls. At full health, ordinary melee is 0% before resistance, but a bite is still 100% and a cloud is still 5%.
Chance before resistance by current health
The action chooses the curve. Current health chooses the point on that curve. These values come before the Responder's infection resistance stat.
| Current health | Zombie melee | Grab begins | Grab bite | Shambler cloud |
|---|---|---|---|---|
| 100 HP | 0% | 0% | 100% | 5% |
| 80 HP | 0% | 0% | 100% | 5% |
| 60 HP | 0% | 0% | 100% | 23% |
| 50 HP | 5% | 0% | 100% | 32% |
| 30 HP | 27.5% | 0% | 100% | 50% |
| 10 HP | 50% | 0% | 100% | 50% |
| 0 HP | 50% | 0% | 100% | 50% |
Walker Zombie, Runner Zombie, Shambler Zombie, Prime Zombie use the same 1x active scalar. The exposure action, not the broad zombie profile, selects the supported curve.
Walker, Runner, Shambler, and Prime all apply a 1.00x scalar to these exposure values. The zombie profile does not create a second set of numbers here. Identify what happened to the Responder, especially whether a grab reached the bite or whether the player remained inside a cloud.
Keep resistance out of the curve result
adds 0.1 to the infection resistance stat. adds 0.2. The base resistance is 0, so the resulting stats are 10% and 20%.
The game does not state how an exposure value and resistance combine into a final probability. A 5% melee curve and a 20% resistance stat do not prove 0%, 4%, or any other final chance. Do not subtract 20 percentage points or multiply by 0.8.
Keep the resistance stat separate
| Skill state | Base resistance | Additive skill value | Resulting resistance |
|---|---|---|---|
| No infection skill | 0% | None | 0% |
| 0% | +10 percentage points | 10% | |
| 0% | +20 percentage points | 20% |
Calculation boundary: the game does not state how an exposure-curve value and this resistance stat become a final chance. Do not subtract or multiply them.
Treat Acquired Immunity as a separate build input. It does not remove the need to heal, break a grab, or leave a cloud. Quote an exact chance only for the pre-resistance exposure curve shown here. No post-resistance probability is stated, so keep the decision to actions you can verify on screen.
Open the Acquired Immunity record or Expert record to inspect the current skill fields. The Responder skill mechanics guide explains how additive skill values and Expert replacement work without turning this resistance stat into a final infection roll.
Use Phalanx Pills as a delay
One bottle of has three doses. Its values are 1.00 base effectiveness, a 0.25 repeated-use reduction, and a 100-second resistance reset. The item can only be used while infected.
Use a ready dose when Gene Therapy needs another infection cycle or when delaying infection is the only supported action in hand. The reason to wait for the reset, when the situation allows it, is the repeated-use reduction. Spending several doses together consumes the bottle while the penalty remains active.
The game gives no exact seconds-gained formula for a penalized dose. Do not turn the 0.25 reduction into a 90-second, 60-second, or 30-second extension. If the previous dose was 30 seconds ago, the reset still needs 70 seconds. Another dose may be the only action available, but do not assume it creates enough time for Gene Therapy.
The failure signal is a dose used while the repeated-use state is not ready and the remaining treatment action still has no proven window. At that point, preserve the Responder’s health, stay with the team, and continue toward a cure. Do not spend the final dose because an invented duration looked sufficient.
Use the Phalanx Pills Inventory record for its current weight, uses, description, and related skill fields. That record answers what the item is. This page answers what the timer fields do and do not support.
Leave time for both Gene Therapy steps
uses two inputs. The first takes a blood sample and begins synthesis. The second administers the prepared cure. The current instruction describes synthesis as about 25 seconds, so the value is approximate.
Use this boundary:
synthesis margin = remaining infection time - about 25 seconds
A positive result means the 120-second cycle contains the stated synthesis period. It does not include travel, equipping the injector, loss of control, or the second input. Start before the margin reaches zero. A zero or negative result means the current cycle does not fund the stated synthesis period by itself.
Current timer and held-treatment boundaries
| Ruleset | Infection duration | Cure duration field | Gene synthesis |
|---|---|---|---|
| Casual | 120 seconds | 60 seconds | About 25 seconds |
| Classic | 120 seconds | 60 seconds | About 25 seconds |
- Doses in one bottle
- 3
- Base effectiveness
- 1
- Repeated-use reduction
- 0.25
- Resistance reset
- 100 seconds
90 seconds elapsed
30 seconds remain
The approximate synthesis window leaves a 5-second mathematical margin. Start held Gene Therapy now, from safety.
105 seconds elapsed
15 seconds remain
The synthesis margin is -10 seconds. A ready Pill dose can delay infection before synthesis; the current cycle alone is too short.
Repeated dose not ready
70 seconds until reset
One dose was used 30 seconds ago. The game gives no exact time gain for another penalized dose, so do not assume it creates a safe synthesis window.
At 90 seconds elapsed, 30 seconds remain and the mathematical margin is 5 seconds. The default is to start now from safety. At 105 seconds elapsed, only 15 seconds remain. If a full-effect Pill dose is ready, use it before synthesis. If a repeated dose is still penalized, the exact new margin is unknown and must not be presented as safe.
Both modes also carry a 60-second Cure duration value, but the game does not give a complete post-cure immunity schedule from it. Do not add it to the infection countdown, use it instead of the second Gene Therapy input, or promise a duration of immunity. The known result is narrower: Gene Therapy is the cure item and requires the two stated steps.
Use the Experimental Gene Therapy Inventory record when you need its current item details. If the treatment is absent, the mechanism does not create a hidden alternative. The next action is to preserve time with a ready Pill dose or keep searching with the team.
Count Resident Genes healing separately
adds 15 HP when Pills are used. It does not target Gene Therapy at the Normal tier. adds 25 HP to Pills and 25 HP to Gene Therapy.
Resident Genes healing is a separate result
| Skill state | Phalanx Pills healing | Gene Therapy healing | What changes |
|---|---|---|---|
| No Resident Genes | 0 HP | 0 HP | Treatment behavior only |
| 15 HP | 0 HP | Pills heal | |
| 25 HP | 25 HP | Both treatments heal |
The HP result does not replace the infection timer result. A Pill can delay infection and heal because of the skill, while Gene Therapy can cure and heal at Expert. Keep those effects as separate outputs.
This healing is not another infection delay. A Pill can change two separate results: its infection treatment behavior and the HP added by Resident Genes. Expert Gene Therapy can also cure infection and add its 25 HP skill effect, but the healing does not perform the second treatment input or set an immunity duration.
The health gain can change the next exposure curve. A Normal Resident Genes dose moves 45 HP to 60 HP if all 15 HP can be received, crossing the ordinary melee curve to 0% before resistance. Expert can move 35 HP to 60 HP with its 25 HP effect. Neither result changes the 100% grab-bite curve or removes the Shambler cloud’s 5% value at high health.
Open the Resident Genes record or Expert record to verify the exact treatment targets. Choose the skill for its healing only when those treatment items are part of the run plan. Acquired Immunity is the alternative when the build decision is about resistance rather than treatment healing.
Use the rule in a live infection
Act in this order:
- Start with the 120-second Casual or Classic infection cycle.
- Identify the exposure action and current health. Use the curve as a pre-resistance value.
- Record Acquired Immunity separately. Do not calculate a final chance.
- Check whether Gene Therapy is held and whether more than its approximate synthesis time remains.
- If the window is too short, check remaining Pill doses and whether the 100-second repeated-use reset is ready.
- Apply Resident Genes healing as its own HP result.
- After a Pill, continue toward Gene Therapy. Delay is not cure.
The default treatment answer is Gene Therapy while the stated window fits. A ready Pill is the fallback when it does not. The cost of the fallback is one dose and the repeated-use state. The alternative when neither item is held is to stay with the team and keep searching, while avoiding contact that spends health and treatment time.
The choice has failed when the cycle expires, Gene Therapy cannot complete its two stated steps within the available time, or the plan depends on an unstated penalized-dose duration. Do not repair that failure with an immunity assumption or a timer copied from another patch.
Know what the rule does not answer
This mechanism covers four exposure curves, the active 1.00x threat scalar, the separate Acquired Immunity stat, the 120-second Casual and Classic infection duration, Phalanx Pills repeated-use fields, the approximate Gene Therapy synthesis boundary, the 60-second Cure duration field, and Resident Genes healing targets.
No final post-resistance infection probability, exact time gain for a penalized Pill dose, interruption behavior, guaranteed loot location, or complete immunity duration after Gene Therapy is stated. Do not base the next action on one of those unknowns.
If infection is active, follow the step-by-step treatment decision for the item and time you have. If the Responder only needs HP, use the Bandages and Medkit healing rule instead. Use the Medical Inventory view to open the treatment you hold, or the Responder skills query to inspect the active infection skill. These records and decisions are current for Hotfix 1.0.4.0. The game facts were checked on September 2, 2026.